Hydraulic hold-down for squaring shears



Jan. 11, 1938. v R, L BROWNLEE 2,105,402

-HYDRAULIC HOLD-DOWN FOR SQUARING' SHEARS Filed Aug. 2, 1935 2 Sheets-Sheet l JIL 11, 1938. R. BRowNLEE 2,105,402

HYDRAULIC HOLD-DOWN FOR SQUARING SHEARS Filed Aug. 2, 1955 2 Sheets-Sheet 2 Z5 L@ Z6 Y Patented Jan. ll, 1938 UNHTED T'ES ATENT OFFliE Robert Leslie Brownlee, Chicago, Ill., assignor to Dreis 5 Krump Mfg. Company, Chicago, Ill.

[application August 2, 1935, Serial No. 34,479

' 7 Claims.

r1his invention relates to squaring shears and the like, and more particularly to hydraulic holddown devices therefor, and my main object is to provide a hold-down apparatus in which a set of self-contained units is employed, each unit having an independent hold-down mechanism. A further object of the invention is to arrange the hold-down units in a simple series and not dependent on any master or basic hydraulic elel0 ment for power.

Another object of the invention is to design the hold-down units with means for self maintenance in a highly efficient condition at all times.

' 15 An additional object of the invention is to provide means whereby a defect in or injury to any of the hold-down units does not disable the balance of the units or the machine for the purpose of holding down the material, An important object of the invention is to so design the hold-down units that they will have an advantageous leverage for the purpose of their function.

With-the above objects in view, and `any others which may suggest themselves from the descrip- Y tion to follow, a better understanding oi the invention may be had by reference to the drawings, in which- Figure 1 is a front View of a portion of a squaring shear, showing the position of the novel holddown apparatus;

Figure 2 is a section on the line 2-2 of Fig, l;

Figure 3 is va cross section onan enlarged scale of one of the hold-down units at the inception of its operation;

Y Figure 4 is a View similar to Fig. 3, showing the unit at the termination ci its operation; and

Figures 5, 6 and 'l are, respectively, sections on the lines 5 5, 6-6 and 'l-'I of Figure 3.

In the development of hydraulic hold-down i0 means for squaring shears, it is customary to employ a master cylinder for the fluid and to pipe the latter to a set of smaller cylinders in the holddown Zone for the control of plungers above the work to be held down. With an arrangement of this kind it is necessary to employ valves and other accessory means in order to properly control the action, vand should any mishap occur in one of the smaller cylinders, or something go wrong with one oi the plungers, the entire mechanism must be laid up for repairs and the shear kept out of operation for some time. I have therefore departed from the customary hydraulic design for the particular purpose, and devised an apparatus which operates efficiently and remains in use despite possible damage to or disability in one or more of the hold-down units.

In carrying out the invention, specic reference to the drawings indicates a typical squaring shear at I, its ram at II, its bed at I2, and its 5 sides at Ia. As shears of this type are standard, the connections ior the operation of the ram have merely been shown in part and need not be described. For the purpose oi the hold-down mechanism, a power shaft I3 running crosswise` 1g of the machine is employed, the same having a series of substantially semi-circular cams I3a at points suitably spaced to induce the operation of a set of hold-down plungers I4.

Each plunger I4 is mounted in an independent 1:, unit represented by a block I5 of substantially square form, the series of blocks being bolted as indicated at I6 between a pair of frame plates I'I carried by the sides lila oi the machine.

Each cam I3a is adapted to bear upon a rolleri i i8 carried by a cross lever I9 whose rear end is pivotally supported at |90. by a hanger 20. The frontal portion of each lever I9 pivotally receives at |91) a depending pin 2| which has a thread at its upper portion to receive a nut 22 with a nutl u, lock 23 above it and `a free washer 24 below it. The balance oi the pin below the washer 24 is taken up by an expansive spring 25. The latter is adapted to bear upon a long bar 26 extending freely between the two frame plates Il. The` 4, bar 2S rests on the head portions 21a of a series u of primary plungers 21.

Each plunger 21 is fitted with a leather or other packing 28 at its lower end, as clearly shown in Fig. 3, to make a snug t in a vertical circular bore I5a in the upper portion of the block I5. The lower end of the bore I5a opens on a circular bore I5b of larger diameter, which continues to the bottom of the block, receiving a closure in the form of a plate 29 secured to the block by screws 30. i

Within the bore I5b is located the hold-down plunger I4, whose head Ida is fitted with a suitable packing Iib to snugly iit the wall of the bore. Between the head of the plunger and the plate 29 is disposed an expansive spring 3l.

The top of the block I5 is sunken at I5c to provide an annular well, the inner wall oi the latter being an upward extension I5d of the stock of the block I5 which forms the wall of the bore 15a. A cross duct I5e extends from the bottom of the well I5c into communication with the bore 55a; also, a similar passage I5f extends outwardly to a tube 32 which rises along side the extension 15d to a high point in the well I5c.

Cal

In the operation of the hold-down mechanism its normalk positions may be considered as indicated in Figs. 2 and 3. It is seen in Fig. 2 that the flat portion of each cam I 3a is now above the related lever I9. The latter is thus at the upper end of its operation and is preferably maintained there by a spring 33 between its front end and the top of the machine I0. However, when the shaft I3 is given a partial turn, the prominent portions of the cam profiles will bear down on the rollers I8 of the levers I9, causing these to press down on the bar 26 through the agency of the pins ZI and the intermediate springs 24. The bar 26 in turn presses down the set of primary plungers 21 which transmit energy through the hydraulic medium in the block bore Ia to the related hold-down plungers All.

Owing to the greater area of the plunger heads I4a. the action of the primary plungers 2l' will impart a correspondingly greater pressure tothe plungers I, procuring a powerful hold-down action on the work. As the stroke of the plunger Mis limited byv the thickness of the work, it is the province of the top springs 25 to take up excess motion in the pins 2|; and the springs 3I are, of course, provided to retract the holddown plungers I@ the moment the pressure from above has been released, such as by a further or reverse partial turn of the mainshaft I3 to restore the cams I3a to the normal position shown, in which event the springs 25 and 33 procure the lifting of the lever I9.

It is seen from the above description that the master control of the hold-down mechanism is mechanical and extends only to the bar 25.

Beyond the latter the hydraulic units are in aseries numbered or spaced as the need may dictate and independent from one another as to action or eifect. Thus, inefficiency or failurein any of therunits will not be Ytransmitted-to the other units; and the removal of any defective units for attention or repair leaves the other units fully able to continue their work, so that the machine need not be out of service at any time. f

The object of the well 50 in the top of each block I5 is to assure the maintenance of the proper amount of hydraulic liquid in the plunger bore I5a. Thus, what liquid may work past the plunger packing 28 will accumulate above the same and eventually flow over the exterior Idd into the Well I 5c. The latter already has a spare supply of the liquid, as indicated in Figs. 3 and 4, which replenishes the supply in lthe bore I5 by way of the .passage I5e. In this connection, the tube 32 serves as anr airvent and relieves such pressure as may resist the entry of the replenishing f luid.

It will be evident that I have provided a holddown mechanism which is vnot a general hydraulic system with pipes, master cylinders, valves and other complications. The machine is ostensibly of simple mechanical design; yet it employs the powerful and advantageous hydraulicY factor, but only in the zone of application and in the simple and desirable unitary form,.whose advantages have been related. A machine so constructed is for the above reasons not only less costly than a fully hydraulic one, but is far more elcient and economical to maintain, since` it need not be laid upfor dismantled in case of disability or failure in one or more of the hold-down elements. Also, the novel mechanism is designed for operation without attention or repair to its hydraulic units, since the liquid in these is a lubricant and is automatically maintained at Working capacity.

I claim:

1. A hold-down mechanism for shears comprising a series of identical units, each unit being in the nature of a block perforated with longitudinally communicating bores of different diameters, a plunger in the smaller bore, a second plunger in the larger bore and forming a holddown element by hydraulic action when a liquid is interposed between the plungers, a single bar extending longitudinally-over the external ends of all of the 'smaller plungers, and means to actuate the bar with the eifect of advancing all of such smaller plungers simultaneously.

' 2. The structure of claim l, and a pair of stationary side bars receiving the series of units between them, said longitudinally extending bar being disposed between said side bars and guided thereby.

3. The structure of claim 1, said bores being vertical, and means in the region of the upper bore to replenish such of the liquid as may escape from the action of the plunger therein.

4. The structure of claim l, said bores being vertical, and means in the region of the upper bore to replenish such of the liquid as may escape from the action of the plunger therein, such means comprising-an upward extension of the Wall of the upper bore and defining an annular well above the extension, and the extension being; transversely perforated to establish communication between the lower portion of the well and said upper bore.

5. The structure of claim 1, said bores being vertical, and means in the region of the upper bore to replenish such of the liquid as may escape from the action of the plunger therein, such means comprising an upward extension of the wall of the upper bore and defining an annular well above the extension, 'the extension being formed with transverse perforaticns between the lower portion of the well and said upper bore, and a vent tube directed from one of the perforations upwardly to terminate above the extension. Y Y i 6. A hold down mechanism yfor shears comprising a series of Work clamping elements, a separate and self contained hydraulic operating unit for each element, each unit comprising a large cylinder and a small cylinder communicat-,v ing therewith, plungers in said cylinders, means engageable with and operable to actuate simultaneously all of said plungers in said small cylinders to transmit power to said larger plungers to actuate the same, and said larger plungers being formed to comprise clamping elements.

V7. A hold down mechanism for shears comprising a series of work clamping elements, a separate and self contained hydraulic operating unit for each element, a primary control plunger for each unit, a secondary plunger for each unit operable by said primary plunger and formed to provide a work clamping portion, and a pressure bar engageable with all of said primary plungers to actuate them simultaneously.

ROBERT LESLIE BROWNLEE. 

